1. Field of the Invention
The present invention relates to a processing method for obtaining continuous operation of a communication control program in a computer system provided with a common memory which can be accessed by an active process and a standby process for executing the communication control program.
2. Description of the Related Art
In a computer system, when a communication access method operated by a communication control program cannot be used because of a hardware malfunction or software failure in the computer system, a user (application program or terminal operator) utilizing the communication control program cannot operate the system continuously due to this malfunction or failure. Accordingly, the user must reestablish a logical connection to a communication terminal, and must restart the operation in order for it to continue. Namely, the user must execute the following complicated steps: restart the communication access method; reestablish the logical connection; examine the effects of the malfunction and recover the process; and restart the operation when the communication access method goes down.
In one obvious method of solving the conventional problems involved, the communication control program is duplicated by an active process and a standby process. The active process operates during normal operation. The standby process, which is not affected by the failure of the active process, is brought from the standby state to operate the program continuously when the active process cannot be operated.
By using a common memory to which both the active process and the standby process have access, and by taking, when the active process fails, all of the data of the connection operational environment or the transmission and reception signals used by the active process, the standby process can continue the operation.
Namely, a continuous operation can be obtained by the following steps. First, when the connection is made, the connection operational environment is stored in the common memory; when data is received, the received data is stored in the common memory; the data is transmitted, and upon completion thereof, the received data is cleared from the common memory; and when the active process becomes inoperative, the operational environment and received data are taken from the common memory by the standby process and the operation is continued.
In the above processing, however, the storing of the received data in the common memory or the clearing of the data affects the performance of the normal operation. Further, since all of the received data is stored, a large capacity common memory is needed. Accordingly, the above steps are not a practical solution to this problem.
The present invention is intended to solve the above problems.